Non-standard manufacturer-specific pinouts

Which JTAG pinout should I choose?

If you are designing with ARM or MIPS microprocessor, we recommend using appropriate JTAG connector (EJTAG or ARM JTAG) to maintain
compatibility with development tools. In other cases we recommend you using JTAG connector for manufacturer of your part or
AVR/Byteblaster JTAG (which is compatible with many other products) or standard 8pin "PLD" JTAG connector.

Daisy chaining multiple devices

If your design uses multiple devices with JTAG TAP, you must either use separate connector for each device or chain devices.
Generally, JTAG supports many devices in single JTAG chain, but many tools are not compatible with this feature. Check
tool's documentation before you put devices into chain.